The deployment of cytotoxic T cells is a crucial part of the body’s adaptive immune defenses against infection. In collaboration with Chris Hunter’s group, we studied the migration of immune cells in tissue, in order to understand how specific biochemical signals, such as chemokines, affect migratory behavior, and in turn, how migration contributes to the immune response.
We analyzed the migratory behavior of CD8+ T cells. We quantitatively characterized the migration statistics of T cells in order to understand their observed behavior in a broader biological context. Interestingly, we found that T cells migration does not conform to simple Brownian walk statistics; rather, they perform generalized Lévy walk, alternating between runs and pauses drawn from a Lévy distribution. This resembles an (evolutionarily conserved?) efficient search strategy utilized by many other organisms.
Interestingly, this differs from our observations of T cells in lymph nodes, which appear to be comprised of two populations, each performing an exponential random walk. This observation raises many new questions about how environmental stimuli (e.g., tissue type or presence of infection) affect T cell searches for targets (whatever they may be).
The video above, made by Penn’s Office of Communications, explains our general results. More detailed information can be found in our paper.
References
- TH Harris*, EJ Banigan*, DA Christian, C Konradt, ED Tait Wonjo, K Norose, EH Wilson, B John, W Weninger, AD Luster, AJ Liu, and CA Hunter (2012) Generalized Lévy walks and the role of chemokines in migration of effector CD8+ T cells. Nature 486: 545-548.
- EJ Banigan, TH Harris, DA Christian, CA Hunter, and AJ Liu (2015) Heterogeneous CD8+ T cell migration in the lymph node in the absence of inflammation revealed by quantitative migration analysis. PLoS Comput. Biol. 11: e1004058.